Selective pulmonary vasodilation induced by aerosolized zaprinast.
BACKGROUND
Zaprinast, an inhibitor of guanosine-3',5'-cyclic monophosphate (cGMP)-selective phosphodiesterase, augments smooth muscle relaxation induced by endothelium-dependent vasodilators (including inhaled nitric oxide [NO]). The present study was designed to examine the effects of inhaled nebulized zaprinast, alone, and combined with inhaled NO.


METHODS
Eight awake lambs with U46619-induced pulmonary hypertension sequentially breathed two concentrations of NO (5 and 20 ppm), followed by inhalation of aerosols generated from solutions containing four concentrations of zaprinast (10, 20, 30, and 50 mg/ml). The delivered doses of nebulized zaprinast at each concentration (mean +/- SD) were 0.23 +/- 0.06, 0.49 +/- 0.14, 0.71 +/- 0.24, and 1.20 +/- 0.98 mg x kg(-1) x min(-1), respectively. Each lamb also breathed NO (5 and 20 ppm) and zaprinast (0.23 +/- 0.06 mg x kg[-1] x min[-1]) in combination after a 2-h recovery period.


RESULTS
Inhaled NO selectively dilated the pulmonary vasculature. Inhaled zaprinast selectively dilated the pulmonary circulation and potentiated and prolonged the pulmonary vasodilating effects of inhaled NO. The net transpulmonary release of cGMP was increased by inhalation of NO, zaprinast, or both. The duration of the vasodilation induced by zaprinast inhalation was greater than that induced by NO inhalation.


CONCLUSIONS
Aerosolization of a cGMP-selective phosphodiesterase inhibitor alone or combined with NO may be a useful noninvasive therapeutic method to treat acute or chronic pulmonary hypertension.
Ichinose
F
F
Department of Anaesthesia and Critical Care, Massachusetts General Hospital, Boston 02114, USA.
Adrie
C
C
Hurford
W E
WE
Bloch
K D
KD
Zapol
W M
WM
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000009:adverse effects; D000280:Administration, Inhalation; D000336:Aerosols; D000818:Animals; D006152:Cyclic GMP / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D006439:Hemodynamics / Q000187:drug effects; D006976:Hypertension, Pulmonary / Q000139:chemically induced; D008168:Lung / Q000187:drug effects*; D009569:Nitric Oxide / Q000008:administration & dosage / Q000494:pharmacology*; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D011652:Pulmonary Circulation / Q000187:drug effects; D011688:Purinones / Q000008:administration & dosage / Q000494:pharmacology*; D012756:Sheep; D014662:Vasoconstrictor Agents / Q000009:adverse effects; D014664:Vasodilation / Q000187:drug effects*
D000336:Aerosols; D004338:Drug Combinations; D010726:Phosphodiesterase Inhibitors; D011688:Purinones; D014662:Vasoconstrictor Agents; D009569:Nitric Oxide; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C011145:zaprinast; D006152:Cyclic GMP